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A very common question I get from people is about the difference between slurry and swarf. What is Slurry? What is Swarf? Here's a quick crash course.

Slurry = Loose particles of sharpening stone abrasive. This is the "paste" that forms when you flatten your sharpening stones and is the color of the stone you are using. Slurry can increase the cutting speed of a sharpening stone.

Swarf = Loose metal particles that are formed when sharpening a knife. This mixes with the slurry while you are sharpening and is blackish or grayish in color. Swarf can increase the polishing effects of a stone, BUT it does not increase the cutting speed of a sharpening stone.

Forming a slurry at lower grits is encouraged because it increases the speed of bevel setting and scratch cleanup. On higher grit stones it is a different story.

On higher grit natural stones, a slurry is encouraged because it will break down and form an even higher grit in the process. This is why some Japanese natural stones span a grit of 6,000 to 10,000 grit, or 10,000 to 15,000 grit, and beyond. On a synthetic stone, however, or when using the "Murray Carter" method of sharpening, a slurry is not encouraged due to the particles running into the fine edge you've created. This can sometimes slightly dull the edge. Synthetic stone particles have a much harder time breaking down, thus, they tend to finish at the grit they were designed for.

Feel free to shoot questions or add to this, please!

_________________Shaun Fernandez

With great sharpness comes great responsibility.

Jmbullman

Post subject: Re: What is Slurry and Swarf?

Posted: Mon Apr 23, 2012 10:01 pm

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Joined: Sun Apr 22, 2012 9:45 pmPosts: 657

I have noticed when u heal to tip backstroke when u are finishing with a stone if the swarf is too bad and u are making say a 8-10 degree bevel unless u wash off the swarf u can dull AND scratch the surface if u get alot of build up while finishing so I always rinse the stone before I do that finish stroke. Just a thought. Jmbullman

_________________Master of the addict 1. In the end their can be only one Jmbullman the freehander.Nubatamas rule the stone world! The freehanderThe most electrifying show stopping man in knife sharpening today!

Jmbullman

Post subject: Re: What is Slurry and Swarf?

Posted: Mon Apr 23, 2012 10:04 pm

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Joined: Sun Apr 22, 2012 9:45 pmPosts: 657

If there is no swarf on a stone I always create it, I believe it aids in cutting power and have even done it halfway through a sharpening session if I felt a difference in the cutting power. Jmbullman

_________________Master of the addict 1. In the end their can be only one Jmbullman the freehander.Nubatamas rule the stone world! The freehanderThe most electrifying show stopping man in knife sharpening today!

Jmbullman wrote:I have noticed when u heal to tip backstroke when u are finishing with a stone if the swarf is too bad and u are making say a 8-10 degree bevel unless u wash off the swarf u can dull AND scratch the surface if u get alot of build up while finishing so I always rinse the stone before I do that finish stroke. Just a thought. Jmbullman

I agree. Especially with stones that don't build any slurry like the Shaptons, swarf can ruin a finish. Clean of those stones!:D

That's why I loves my nats Don't get me wrong I like to play in the mud with all of my stones, but on naturals the more mud the better.

Jmbullman

Post subject: Re: What is Slurry and Swarf?

Posted: Tue Apr 24, 2012 11:55 am

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Joined: Sun Apr 22, 2012 9:45 pmPosts: 657

I love naturals too, are there any that u have used that will work on the addict 1's from start to finish. If so please tell me I have every comity and type of ark out their plus a yogonoshima and a monzen. I would love to be able to work o. Addicts with naturals but sometimes it a 3 or more hour job just on the shaptons. Jmbullman

_________________Master of the addict 1. In the end their can be only one Jmbullman the freehander.Nubatamas rule the stone world! The freehanderThe most electrifying show stopping man in knife sharpening today!

i tried a few naturals on my addict 1, but there are few naturals that will cut that steel effeciently from start to finish. However, adding a 15° microbevel with a Yaganoshima Asagi works really well. I think you have a slice from the same stone as mine came from.

For reprofiling, or doing multiple Addicts, I would still go for Shaptons.

A Shapton 120 or 220 with a heavy slurry raised by a DMT XXC will cut lightning fast. If you are doing heavy reprofiling work you may need to clean the stone a couple of times and raise fresh slurry once it gets too dark. Sometimes splashing a little more water on the stone is all that is needed. It's up to the user to determine this, and also how well the user knows the stone, the steel, and the bevel he or she is trying to create.

_________________Shaun Fernandez

With great sharpness comes great responsibility.

Jmbullman

Post subject: Re: What is Slurry and Swarf?

Posted: Tue Apr 24, 2012 6:43 pm

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Joined: Sun Apr 22, 2012 9:45 pmPosts: 657

Michiel I have the full size stone and I never though about making a microbevel on one and Shaun I just tried that trick it cut an hour off cutting this addict. Michiel am going to send u a couple of pics I can't load with my camera phone unfortunately. It turned out great

_________________Master of the addict 1. In the end their can be only one Jmbullman the freehander.Nubatamas rule the stone world! The freehanderThe most electrifying show stopping man in knife sharpening today!

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